The present invention relates to a composite-construction roll, including a roll frame reinforced with reinforcing fibers, the reinforcing fibers are arranged in a spiral inside the matrix material. The invention also relates to a method for manufacturing a composite-construction roll and to a special use of the roll.
European patent publication 363887 discloses one method for manufacturing a composite-construction roll. Generally, such a roll is manufactured on top of a suitable form by winding reinforcing fibers spirally around the form and simultaneously feeding the matrix material, usually a suitable resin. When manufacturing large rolls, the problem arises of not knowing the degree of hardening of the matrix material. This knowledge is important, because finishing that is started too early will damage the roll frame.
Other composite-construction rolls are disclosed in Finnish patent publications FI 94403 and FI 100264.
In roll manufacturing, there is a great need to understand the hardening event and to control manufacture more precisely. Uncontrolled hardening shrinkage distorts the shape of the roll and causes unnecessary residual stresses, which reduce the roll""s service life. Controlled manufacture and subsequent monitoring of the roll are key factors in increasing reliability. In the case of composite rolls, information is needed from other parts of the roll as well as from the surface. This is especially so, as unlike in a metal structure, a composite roll""s most critical point is not necessarily on its surface.
During operation, it is important to know the stresses acting in the roll, both to be able to monitor the roll""s loading and for possible process control. PCT application publication WO 96/25288 discloses one system intended for monitoring nip loads, one embodiment of which uses optical fibers set into the surfacing to measure stress. Though such a sensor will certainly show the nip load, it will not show the stresses acting in the roll.
The present invention provides an entirely new kind of composite-construction roll and a method for manufacturing it, which will permit the manufacture of a better composite-construction roll and give advantages when using it.
More specifically, a composite-construction roll includes a roll frame reinforced with reinforcing fibers, characterized in that among the reinforcing fibers there is at least one optical fibre and that the roll includes terminals arranged in this optical fibre for a transmitter and a receiver for measuring a selected optical quantity from the fibre.
A method for manufacturing a composite roll, in which composite roll there is a roll frame and a possible surfacing and in which manufacturing of the roll frame the reinforcing fibers are fed simultaneously with the matrix material is characterized in that at least one optical fibre is fed among the reinforcing fibers.
The use of a composite roll in a paper/board or finishing machine, in which the roll drives or only supports the fabric, is characterized in that the measurement of the stress in the roll is used to measure the tension of the fabric.
Placing optical fibers among the reinforcing fibers will ensure that they become located inside the roll frame and will permit monitoring of internal events in the roll frame. Other benefits and embodiments of the invention appear in connection with the following examples.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.